Área Bioquímica y Biología Molecular, Universidad de La Rioja, Logroño, Spain.
J Antimicrob Chemother. 2012 Feb;67(2):330-4. doi: 10.1093/jac/dkr497. Epub 2011 Nov 28.
The clonal lineages, resistance mechanisms and virulence traits of tetracycline-resistant (Tet(R)) methicillin-resistant Staphylococcus aureus (MRSA) strains isolated in a Spanish hospital during 2009 and 2010 were investigated.
Fifty-two Tet(R) MRSA strains from unrelated patients were included in this study. Susceptibility to 26 antimicrobial agents was determined and 24 resistance genes were tested for by PCR. The sequences of the genes grlA and gyrA were analysed in all ciprofloxacin-resistant MRSA isolates. For all strains, spa, SCCmec and agr typing was implemented. Multilocus sequence typing was performed for 16 representative strains of the different spa types. The presence of the genes tst, lukF/lukS-PV, eta, etb, etd and cna was investigated by PCR.
Fifteen different spa types, four of them new ones, were detected among the 52 strains, being associated with the following clonal complexes (CCs): CC398 (67.3%), CC1 (11.5%), CC5 (11.5%) and CC8 (9.6%). A novel sequence type (ST), ST2077, belonging to CC398 was identified. Most MRSA CC398 strains were typed as SCCmecV-agrI. In addition to β-lactam resistance, isolates showed resistance to (gene/number of strains): tetracycline [tet(K)/36, tet(L)/8 and tet(M)/48], macrolides and lincosamides [erm(B)/6, erm(C)/25, erm(T)/2, msr(A)/msr(B)/4 and mph(C)/4], aminoglycosides [aac(6')-Ie-aph(2')-Ia/8, ant(4')-Ia/13 and aph(3')-IIIa/15], trimethoprim [dfrS1/2 and dfrK/3] and mupirocin (mupA/3). Strains investigated for mutations mediating quinolone resistance revealed an S80F exchange in GrlA and different changes in GyrA. Three strains were Panton-Valentine leucocidin-positive (ST8 and ST94) and 41 strains were cna-positive. All MRSA isolates were negative for the genes tst, eta, etb and etd.
Tetracycline resistance could be a good marker for MRSA CC398, although this resistance can also be found in other lineages.
研究 2009 年至 2010 年期间西班牙一家医院分离的耐四环素（Tet（R））耐甲氧西林金黄色葡萄球菌（MRSA）菌株的克隆谱系、耐药机制和毒力特征。
本研究纳入了 52 株来自无关患者的 Tet（R）MRSA 菌株。通过 PCR 检测了 24 种耐药基因，并检测了 26 种抗菌药物的敏感性。对所有环丙沙星耐药的 MRSA 分离株进行了 grlA 和 gyrA 基因序列分析。对所有菌株进行 spa、SCCmec 和 agr 分型。对 16 株不同 spa 型的代表性菌株进行了多位点序列分型。通过 PCR 检测了 tst、lukF/lukS-PV、eta、etb、etd 和 cna 基因的存在情况。
在 52 株菌株中检测到 15 种不同的 spa 型，其中 4 种为新型，与以下克隆复合体（CC）相关：CC398（67.3%）、CC1（11.5%）、CC5（11.5%）和 CC8（9.6%）。鉴定出一种新型序列型（ST），ST2077，属于 CC398。大多数 MRSA CC398 菌株被分型为 SCCmecV-agrI。除了对β-内酰胺的耐药性外，分离株还表现出对（基因/菌株数）：四环素[tet（K）/36、tet（L）/8 和 tet（M）/48]、大环内酯类和林可酰胺类[erm（B）/6、erm（C）/25、erm（T）/2、msr（A）/msr（B）/4 和 mph（C）/4]、氨基糖苷类[aac（6'）-Ie-aph（2'）-Ia/8、ant（4'）-Ia/13 和 aph（3'）-IIIa/15]、甲氧苄啶[trimethoprim dfrS1/2 和 dfrK/3]和莫匹罗星（mupA/3）的耐药性。对介导喹诺酮类耐药性的基因突变进行研究的菌株显示 GrlA 中的 S80F 交换和 GyrA 的不同变化。3 株菌株为 Panton-Valentine 白细胞毒素阳性（ST8 和 ST94），41 株菌株为 cna 阳性。所有 MRSA 分离株均为 tst、eta、etb 和 etd 基因阴性。
尽管四环素耐药性也可能存在于其他谱系中，但 Tet（R）可作为 MRSA CC398 的良好标志物。
